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COMPASS Wednesday
COMPASS WEDNESDAY

Combined OCE MPO ATM Seminar Series

SPRING 2024
Wednesdays at 3:00 pm, Seminar Room SLAB 103 / Virtual SLAB 103
(unless stated otherwise)

Jan 17: NO SEMINAR

Jan 24: SPECIAL ATM & OCE FACULTY PRESENTATION SERIES

Dr. Sharanya Majumdar
Department of Atmospheric Sciences, Rosenstiel School

An Unpredictable Journey Into Hurricane Predictability Research
Recording Available at COMPASS ON DEMAND

In this talk, I will start out by discussing some chance occurrences that eventually led me into hurricane predictability research.  Following the principles set out in Lorenz's legendary papers from the 1960s, I will first introduce my early research career phase on "targeted observations", which combined fieldwork, satellite and aircraft observations, data assimilation, and ensemble forecasting.  In the second half of the talk, I will raise a series of research questions tackled by past and present group members on genesis, track, and intensity change, with an increasing emphasis on connecting predictability to physical processes on multiple scales.

Jan 31: SPECIAL ATM & OCE FACULTY PRESENTATION SERIES

Dr. Amy Clement
Department of Atmospheric Sciences, Rosenstiel School

From Slow Science to Usable Science:
The Challenge of Projecting Climate Hazards
Recording Available at COMPASS ON DEMAND

As climate scientists, we are increasingly being asked to weigh in on the question of 'what will climate change look like for me / my home / my community / my company, etc.?' What I will present is an in-progress story about how I have come to approach this question. I will focus on research from the last several decades of good old-fashioned climate dynamics, and what the challenges are that make this a difficult, thus 'slow' problem. The discussion of the scientific challenges will be informed by my experiences working with a range of applied researchers and decision makers working to adapt to a rapidly changing climate with increasingly costly and inequitable risks.

Feb 07: Dr. Alexander Soloviev
Nova Southeastern University, Dania Beach, Florida

Physical Oceanographic Aspects of Upwelling Events
on the Southeast Florida Shelf
Alexander Soloviev, Alfredo Quezada, Megan Miller, Bernhard Riegl, and Richard Dodge
Recording Available at COMPASS ON DEMAND

Coral reef benthic communities are acutely sensitive to changes in environmental parameters such as temperature and nutrient concentrations. Physical oceanographic processes that induce the coastal upwelling therefore act as drivers of community structure on tropical reefs. The cause and frequency of upwellings and how they impact coral communities on the Southeast Florida shelf, however, are not fully understood. The classical wind induced coastal upwelling is not typical for western boundary current regions like the Straits of Florida. We have nevertheless observed prominent upwelling events during hurricane conditions. For example, during Hurricane Wilma 2005 a 4°C drop of the bottom water temperature was registered at an 11 m isobath on the Broward County shelf. Upwelling events can also be caused by internal wave solitons breaking on the continental shelf; an example is the upwelling on Conch Reef that has been studied experimentally (Leichter et al. 1996) and modeled with computational fluid dynamics tools (Miller et al. 2023). Another potential upwelling mechanism is associated with the southward jet attached on the Southeast Florida shelf (Soloviev et al. 2017), which lifts the cold deeper water towards the coast due to the Coriolis effect. This process is being elucidated from a year-long series of glider transects on the shelf between Ft. Lauderdale and Jupiter, FL (Quezada et al. 2023). The upwelling events bringing cold and rich with nutrients water to the coral reef benthic communities may alter, suppress, or provide a natural buffer against climate impacts and could potentially enhance the efficacy of spatial management and reef conservation efforts (Zhu et al. 2022).

Feb 14: Daniel Melo Costa Santos
Guest of Tiago Bilo, CIMAS
Oceanographic Institute, University of Sao Paulo, Brazil

Abyssal Warming and Freshening Process Drives the
Contraction and Homogenization of the AABW in the Argentine Basin
Recording Available at COMPASS ON DEMAND

This study investigates changes in abyssal water properties, with a specific focus on the Antarctic Bottom Water (AABW), using data collected in the northwest Argentine Basin from 2009 to 2022, along 34.5°S, at a trans-basin mooring line known as the South Atlantic Meridional Overturning Circulation Basin-wide Array (SAMBA). The analysis centers at the three most frequently sampled locations: 48.5°W, 47.5°W, and 44.5°W, where pressure-equipped inverted echo sounders are installed and identified as Sites BB, C, and D, respectively. The results reveal an increase in the potential temperature and a simultaneous decrease in salinity at abyssal depths across all locations, except at Site BB. There, a positive change is observed near the bottom, followed by a negative change just above it. A decrease in the buoyancy frequency (N) is detected in the region commonly occupied by the AABW at Sites C and D, while at Site BB, the changes are positive along the profile. The temperature variations are predominantly influenced by vertical movements of isopycnals (heave) rather than changes along them (spiciness). As a result of these abyssal variations, the AABW contracted and freshened at Sites C and D, as its colder layer descended faster than its warmer layer, resulting in a downward expansion of the latter. At Site BB, the AABW also freshened, but with a smaller rate.

Feb 21: NO SEMINAR

Feb 28: NO SEMINAR

Mar 06 (MSC 365): POSTER SESSION

Beron-Vera

Nolan et al.

Olascoaga et al.

Perez & Zuidema

Pita et al.

Shay et al.

Tornow & Ballard

Yang et al.

Mar 13: NO SEMINAR (Spring Recess)

Mar 20: Lev Looney
NOAA-AOML & Department of Atmospheric Sciences, Rosenstiel School
(one-hour MPO student seminar)

Observing and Modeling the Air-Sea Interface Beneath Tropical Cyclones
Recording Available at COMPASS ON DEMAND

Ocean conditions play a critical role in the intensification of tropical cyclones (TCs), and in most cases the feedback to the atmosphere from TC-induced sea surface temperature (SST) cooling cannot be ignored. It is known that stronger, more slowly moving TCs generate more SST cooling, as do stronger ocean temperature stratification and a thinner mixed layer. However, the relative importance of these factors, and the role of TC size, have not been quantified. Based on ocean mixed layer model experiments and global observational datasets, we show that the duration of wind forcing is the limiting factor for TC-induced SST cooling. Further, we find that the thermodynamic effect (changes in vertical temperature gradient with density gradient held constant) is 2-3 times that of the mixing effect (changes in density stratification with temperature stratification held constant). We also find that storm size has a greater influence on the amount of cooling than intensity. In efforts to expand our knowledge of TCs and their coupling with the ocean, several in-situ observational campaigns are carried out during the Atlantic hurricane season. The second part of the presentation will discuss the NOAA-Saildrone hurricane missions, focusing on data quality assessments and validation. Overall, the comparisons across numerous platforms, variables, and ocean-atmosphere conditions show the high quality and value of the saildrone measurements while also revealing unique challenges associated with multiplatform intercomparisons in extreme conditions. These observations are used in a variety of ways to improve our understanding of the air-sea interface beneath TCs.

Mar 25 (Monday, 11:00, Library Map & Chart Room): Dr. Mariana Bernardi Bif
Invited Speaker of the Department of Ocean Sciences
Research Specialist
Monterey Bay Aquarium Research Institute, Moss Landing, California

Constraining the Biogeochemistry of Marine Systems With BGC-Argo Floats
Recording Available at COMPASS ON DEMAND

The deployment of hundreds of robotic floats equipped with chemical sensors in the global oceans is revolutionizing the way we constrain the biogeochemical cycles. In addition to temperature and salinity found in Core Argo floats, BGC-Argo floats are equipped with up to six other sensors. To date, BGC-Argo floats have collected more profiles of nitrate, a key nutrient for ocean productivity, than all oceanographic cruises combined. A float's ability to sample at high spatio-temporal resolution is elucidating biogeochemical processes at remote locations and in areas affected by extreme climate events. In this talk I will provide an overview of BGC-Argo floats, the state of the global array, and the power behind a multi-platform approach to observe marine biogeochemical cycles. I will provide examples of float data used to constrain the biogeochemistry of marine systems that are sensitive to changes from heatwaves, ENSO conditions, and deoxygenation. I will wrap-up the talk with an overview of what's on the horizon for investigating the marine system with floats, and how to train the next generation of professionals to use BGC-Argo and other large ocean datasets.

Mar 27 (11:00, Library Map & Chart Room): Dr. Wokil Bam
Invited Speaker of the Department of Ocean Sciences
Postdoctoral Investigator
Woods Hole Oceanographic Institution, Massachusetts

Understanding Particle Export in the Western Arctic Ocean
and the Northern Gulf of Mexico

The ocean's biological carbon pump, driven by the production and transfers of particulate organic carbon (POC) from surface to the deeper ocean, is a key atmospheric CO2 sink. This pump has various components from physics to ecology that together control its efficiency in exporting particles. Hence, the influence of climate change on the functioning and magnitude of the pump is complex, non-linear, and heterogeneous on a spatial scale. This presentation assesses the pump's status and particle dynamics in two regions facing rapid climate shifts: the Arctic and the northern Gulf of Mexico (nGOM). In the Arctic, particle composition is rapidly changing due to increased primary productivity, sea ice loss, and more shelf-derived materials. The nGOM sees altered particle inputs from coastal erosion and rivers. Both represent the shallow shelf dominated by large river input and represent areas with major changes due to changes in freshwater inputs (nGOM and Arctic) and ice melting (Arctic). POC fluxes in these two contrasting continental shelves were estimated using naturally occurring 210Po-210Pb radioisotope tracers that provide flux estimates integrated over seasonal time scale. 210Po-210Pb radioisotope pair has been extensively used to study particle scavenging, cycling and transport in the ocean. However, the role of particle composition and concentration in the scavenging and sorption of 210Po-210Pb needs to be better understood to successfully utilize these radionuclides as oceanographic tracers. The first part of the talk will focus on the influence of particle composition and concentration on distribution of 210Po and 210Pb whereas the second part will focus on vertical fluxes of POC.

Mar 27: Paul Wojtal
Department of Ocean Sciences, Rosenstiel School
(one-hour OCE student seminar)

Uncovering the Importance of Heterotrophic Bacteria and Varying
Phytoplankton Communities for Particulate Carbon Export in the Northeast Pacific

Phytoplankton form the base of marine food webs in the epipelagic and contribute substantially to suspended and sinking particulate organic matter (POM) throughout the water column, thus sequestering carbon in the deep sea through the biological carbon pump. The biomass of bacterial consumers also may contribute significantly to these particle pools. The fate of POM – for instance, the depth at which it is remineralized – ultimately affects global climate and the carbon cycle. However, it has been difficult to link the biological origins of POM, such as proportional contributions of phytoplankton and bacteria, to its fate, due largely to significant alteration processes occurring as the POM sinks or is advected downward. To examine the origins of POM more closely, I will present the results of multiple geochemical and isotopic measurements of sinking particles from sediment traps and size-fractionated particles from in situ filtration between the surface and 500 m at Ocean Station Papa, collected during NASA EXPORTS (EXport Processes in the Ocean from RemoTe Sensing). From these particles, I examine the carbon isotope composition of amino acids from proteins, the relative concentration of D and L enantiomers of alanine, and the carbon isotope composition of phytol, cleaved from chlorophyll. In combination with my previous results of amino acid nitrogen isotope analysis, I use the D and L enantiomer ratios and the essential amino acid carbon isotope "fingerprints" to estimate the proportional contribution of bacteria to four different POM size fractions. I additionally use the d13C value of phytol to identify material of photosynthetic origin from the upper vs. lower euphotic zone. I will discuss how these results are helping me disentangle the sources of carbon that are the most important to POM in the mesopelagic, and thus are fueling midwater communities and contributing to carbon sequestration.

Apr 01 (Monday, 11:00, Library Map & Chart Room): Dr. Mojtaba Fakhraee
Invited Speaker of the Department of Ocean Sciences
Postdoctoral Researcher
Department of Earth and Planetary Sciences & Yale Center for Natural Carbon Capture
Yale University, New Haven, Connecticut

Ocean's Carbon Cycle: Past, Present, and Future

Throughout Earth's history, atmospheric oxygen and carbon dioxide levels (pO2 and pCO2) have been the pivotal factors controlling the habitability of our planet. The ocean's carbon cycle plays a major role in regulating pO2 and pCO2. Despite its significance, the history of the ocean's carbon cycle and its response to shifts in global average temperature and biotic innovations remain poorly constrained. Moreover, there are still gaps in our knowledge about the potential role of the marine carbon cycle in mitigating the impact of anthropogenically-induced increases in global temperature. In the first part of my talk, I will present results that suggest shifts in temperature and oxygen play a larger role than shifts in ecosystem structure in driving changes in carbon export efficiency in the ocean. In the second part of my talk, I will present findings from a suite of biogeochemical models that underscore the substantial capacity of the modern marine carbon cycle to mitigate the impacts of climate change. Specifically, I will discuss that while there is considerable potential for marine enhanced silicate weathering in sequestering anthropogenic carbon, there are some potential environmental impacts on the marine organisms that need to be considered. Further, I will present results from time-varying reactive transport modeling that suggests a potentially important role of the restoration of the coastal blue carbon ecosystems (e.g., mangroves, seagrasses) in driving ocean alkalinity enhancement and capturing atmospheric CO2 with co-benefits on marine biodiversity and ecosystem services.

Apr 03: Lillian Henderson
Department of Ocean Sciences, Rosenstiel School
(one-hour OCE student seminar)

Apr 08 (Monday, Auditorium): Dr. Agustinus Ribal
Guest of Brian Haus, Department of Ocean Sciences

Department of Mathematics, Hasanuddin University, Makassar, Indonesia

Apr 10 (11:00, Library Map & Chart Room): Dr. Bo Yang
Invited Speaker of the Department of Ocean Sciences
Rosenstiel School of Marine, Atmospheric, and Earth Science, University of Miami

Apr 10: Leah Chomiak
Department of Ocean Sciences, Rosenstiel School
(one-hour MPO student seminar)

Apr 11 (Thursday, 2:30): Dr. Siyuan Wang
Invited Speaker of the Department of Atmospheric Sciences
Cooperative Institute for Research in Environmental Sciences (CIRES), University of Colorado, Boulder,
and NOAA Earth System Research Laboratory (ESRL), Boulder, Colorado

Apr 17: Chong Jia
Department of Ocean Sciences, Rosenstiel School
(one-hour MPO student seminar)

Apr 19 (Friday, 2:30): Dr. Zichong Chen
Invited Speaker of the Department of Atmospheric Sciences
Harvard University, Cambridge, Massachusetts

Apr 24: Ivenis Pita
Department of Atmospheric Sciences, Rosenstiel School
(one-hour MPO student seminar)

May 01: Dr. Milan Curcic
Department of Ocean Sciences, Rosenstiel School

Dispersion of Short Waves Riding on Longer Waves